A fortuitous combination of technical incompetence, political dildoing, and the usual cloud of confusion enables the Bush administration to lose critical emails. The detailed story can be found here at ArsTechnica. Excerpt:

"The case of the missing e-mail
A federal magistrate judge on Thursday chastised the Bush administration for failing to fully answer questions related to a long-running dispute over missing White House emails. The White House is facing lawsuits from two public interest groups, Citizens for Responsibilty and Ethics in Washington and the National Security Archive at George Washington University, demanding that the White House restore the missing e-mails and put in place systems to prevent further e-mail losses. Administration officials were ordered to provide detailed information about the burdens involved in taking immediate actions to preserve copies of hard drive, tapes, and other media that may contain copies of the missing e-mails. ..."